How do you write

40/25
as a percentage?

What percent of 40 is 25? 
Let x = what percent 
of = multiplication 
is means = 
We now write it in math terms: 
x times 40 = 25 

40x = 25 
Divide both sides by 40 to find x. 
x = 25/40 
x = 0.625 
Change the decimal number 0.625 to a percent. 
x = 62.5%